Abstract

pH-responsive interpenetrating polymeric network microgels (IPNMGs) were developed from a combination of a natural
carbohydrate polymer, chitosan (CS), with newly synthesized poly(vinyl alcohol)-g-poly(2-hydroxy-4-N-methylamidobenzoic
acid) (PVA-g-HMA). The IPNMGs were developed using a water-in-oil emulsion method with glutaraldehyde as a crosslinker.
5-fluorouracil (5-FU), an anticancer drug, was encapsulated successfully into these IPNMGs through an in situ method. The
grafting and grafting yield for PVA-g-HMA were found to be 103% and 91.63%, respectively. The formation of IPNMGs and
the structural interactions of pristine IPNMGs and 5-FU-loaded IPNMGs were characterized by Fourier-transform infrared
spectroscopy, differential scanning calorimetry, and X-ray diffraction. Optical microscopy and scanning electron microscopy
revealed the IPNMGs to be spherical and 20 μm in size with a smooth surface. The pH-responsive nature of the IPNMGs
was examined from equilibrium swelling studies under different pH conditions. The in vitro release behavior of the IPNMGs
was examined in pH 1.2 and 7.4 buffer media. The in vitro release results of the pH-responsive IPNMGs showed that they
can be applied to the oral controlled release of 5-FU. The release kinetics of 5-FU was analyzed using the Peppas equation to
understand the nature of the drug release mechanism.